Method of making a sand screen on a base pipe

ABSTRACT

A rod-based well screen is formed in place on a perforated pipe base by wrapping wire around the pipe base and a plurality of rods located around the outside of the pipe. The wire is welded sequentially to each individual rod as it is wrapped around the pipe. The welding and ground electrodes engage the wire and the rods respectively. The rod engaging ground electrode is positioned a short distance ahead of the wire being wrapped around the rods and the pipe base. The ground electrode includes a plurality of contacts. Each contact is mounted to pivot toward and away from a rod. Springs urge each contact toward a rod to hold the rod against the outside surface of the pipe base and to maintain good electrical contact between the contact and the rod. Each contact has a groove to guide the rod into position for welding to the wire.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.60/948,210, filed Jul. 6, 2007, entitled “Manufacturing of SandScreens.”

TECHNICAL FIELD

The present invention relates generally to recovery of hydrocarbons insubterranean formations, and more particularly to tools, systems, andmethods for manufacturing of sand screen assemblies.

BACKGROUND

Hydrocarbon fluids such as oil and natural gas are obtained from asubterranean geologic formation, referred to as a reservoir, by drillinga well that penetrates the hydrocarbon-bearing formation. Once awellbore has been drilled, the well must be completed beforehydrocarbons can be produced from the well. A completion involves thedesign, selection, and installation of equipment and materials in oraround the wellbore for conveying, pumping, or controlling theproduction or injection of fluids. After the well has been completed,production of oil and gas can begin.

Sand or silt flowing into the wellbore from unconsolidated formationscan lead to an accumulation of fill within the wellbore, reducedproduction rates and damage to subsurface production equipment.Migrating sand has the possibility of packing off around the subsurfaceproduction equipment, or may enter the production tubing and becomecarried into the production equipment. Due to its highly abrasivenature, sand contained within production streams can result in theerosion of tubing, flow lines, valves and processing equipment. Theproblems caused by sand production can significantly increaseoperational and maintenance expenses and can lead to a total loss of thewell.

One means of controlling sand production is the placement of relativelylarge grain sand (i.e., “gravel”) around the exterior of a slotted,perforated, or other type liner or sand screen. The gravel serves as afilter to help assure that formation fines and sand do not migrate withthe produced fluids into the wellbore. In a typical gravel packcompletion, a sand screen is placed in the wellbore and positionedwithin the unconsolidated formation that is to be completed forproduction. The sand screen is typically connected to a tool thatincludes a production packer and a cross-over, and the tool is in turnconnected to a work or production tubing string. The gravel is mixedwith a carrier fluid and pumped in slurry form down the tubing andthrough the crossover, thereby flowing into the annulus between the sandscreen and the wellbore. The carrier fluid in the slurry leaks off intothe formation and/or through the sand screen. The sand screen isdesigned to prevent the gravel in the slurry (and other contaminatessuch as sand and silt) from flowing through it and entering into theproduction tubing. As a result, the gravel is deposited in the annulusaround the sand screen where it forms a gravel pack. It is important tosize the gravel for proper containment of the formation sand, and thesand screen must be designed in a manner to prevent the flow of thegravel through the sand screen.

Sand screen types may include wire-wrapped and wire-mesh screen. Awire-wrapped screen generally includes a relatively fine wire wrappedand spot welded to an underlying tubular with interstitial spacesbetween adjacent wires, whereby the interstitial spaces are sized toprevent particles of a predetermined size from passing through thewire-wrapped screen. Examples of wire wrapping techniques are disclosedin U.S. Pat. No. 3,275,785 and U.S. Pat. No. 4,314,129, which are bothincorporated herein by reference. The screen generally circumscribes alength of perforated pipe known as a base pipe. Accordingly, ahydrocarbon fluid (e.g., oil) is permitted flows through the wire-meshscreen and a percentage of particulate matter is filtered from passingthrough. The perforations along the side of the base pipe allow thefluid to enter into a production tubing. In other sand screenembodiments, the screen circumscribes a solid base pipe having an inflowcontrol device for regulating the inflow of fluids into the base pipe.

The present invention includes various embodiments of tools, systems,and processes for the manufacturing of such sand screens.

SUMMARY

Embodiments of the present invention include a wire-wrapping assemblyfor making a sand screen using wire on a base pipe having a plurality ofrods extending along an outside surface of the base pipe. Thewire-wrapping assembly may include: (1) a pipe support for supportingthe base pipe and applying a rotation around the longitudinal axis ofthe base pipe; (2) a wire feeder adapted to wrap the wire around theoutside of the pipe and the rods in spaced helical coils; (3) a firstelectrode positioned to engage the wire and weld the wire to each rod asthe wire is wrapped around the rods; and (4) a second electrode having amounting ring and a plurality of separate individual contacts with eachindividual contact engaging only one of the rods, the mounting ringhaving an inner diameter larger than an outer diameter of the base pipe,each contact being adapted to move radially inward and outward along themounting ring to engage and disengage with the rods, wherein the firstelectrode and second electrode define an electrical circuit as the wireengages each rod to weld the wire to the rods. In general, the base pipeincludes an obstruction (e.g., termination ring, load ring, nozzle ring,end ring, etc.) protruding radially outward beyond the outer diameter ofthe base pipe. The inner diameter of the mounting ring is sufficientlylarge to permit the obstruction to pass therethrough.

In certain embodiments, each contact includes a dovetail-shapedprotruding profile formed along a surface, and the mounting ringincludes a dovetail-shaped groove formed on a face of the mounting ringfor each contact, the mounting ring adapted to receive the profile ofthe contact within the groove to enable sliding of the contact.

In alternative embodiments, each contact includes a dovetail-shapedgroove formed along a surface, and the mounting ring includes adovetail-shaped protruding profile formed on a face of the mounting ringfor each contact, the mounting ring adapted to engage thedovetail-shaped groove of each contact with each protruding profile onthe face of the mounting ring to enable sliding of the contact.

In yet another embodiment, each contact is connected to the mountingring by means of a pinned connection.

In further embodiments, a wheel is arranged proximate the contacts ofthe second electrode, the wheel adapted to apply a force to one contactat a time when such contact engages one of the rods.

The present invention still further includes a method of making a sandscreen on a base pipe having an obstruction protruding radially outwardfrom the base pipe. One embodiment of such method includes the followingsteps: (1) mounting the base pipe for rotation around its longitudinalaxis; (2) positioning a plurality of rods along the outer surface of thebase pipe; (3) rotating the base pipe and the rods to wrap a wire inspaced helical coils around the base pipe and the rods; (4) welding thewire to the rods as the wire engages the rods; (5) providing a set ofcontacts for grounding the rods; (6) grounding each individual rod aheadof the wrapped wire through a separate individual contact that engagesonly said individual rod on the outside surface of the rod adjacent thewire; and (7) moving (e.g., sliding or rotating) the contacts radiallyoutward to clear the obstruction. Another embodiment of such methodincludes providing a wheel to apply a force against the back of thecontact to facilitate a stronger contact engagement to the rod.

Other or alternative embodiments of the present invention will beapparent from the following description, from the drawings, and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which these objectives and other desirable characteristicscan be obtained is explained in the following description and attacheddrawings in which:

FIG. 1 illustrates a profile view of a prior art mechanism formanufacturing a wire-wrapped screen as shown in U.S. Pat. No. 4,314,129.

FIG. 2 illustrates a view of a wire-wrapped sand screen assembly havingend rings between the wire-wrapped sections.

FIGS. 3A-3B illustrate a cut-away view of an embodiment of a wirewrapping assembly in accordance with the present invention for a slidingwelding contact.

FIGS. 4A-4B illustrate a cross-section view of an embodiment of a wirewrapping assembly in accordance with the present invention for a slidingwelding contact.

FIG. 5 illustrates a cut-away view of an embodiment of a wire wrappingassembly in accordance with the present invention for a pivoting weldingcontact.

FIG. 6 illustrates a cut-away view of an embodiment of a wire wrappingassembly in accordance with the present invention for providing animproved weld current path.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

In the specification and appended claims: the terms “connect”,“connection”, “connected”, “in connection with”, and “connecting” areused to mean “in direct connection with” or “in connection with viaanother element”; and the term “set” is used to mean “one element” or“more than one element”. As used herein, the terms “up” and “down”,“upper” and “lower”, “upwardly” and downwardly”, “upstream” and“downstream”; “above” and “below”; and other like terms indicatingrelative positions above or below a given point or element are used inthis description to more clearly describe some embodiments of theinvention. Moreover, the term “sealing mechanism” includes: packers,bridge plugs, downhole valves, sliding sleeves, baffle-plugcombinations, polished bore receptacle (PBR) seals, and all othermethods and devices for temporarily blocking the flow of fluids throughthe wellbore. Furthermore, while the term “coiled tubing” is usedthroughout, it could actually be replaced by jointed tubing or anyrelatively small diameter tubing for running downhole.

Generally, various embodiments of the present invention include animproved current path in the welding process in a wire-wrapped sandscreen manufacturing operation and a method and apparatus for wrappingwire around a sand screen assembly wherein the tubular assembly isformed of components having different diameters.

Wire-wrapping machines for wrapping and welding wire around a tubularstructure (e.g., a perforated base pipe) using pipe handling/rotatingsupport equipment are known in the industry. With reference to FIG. 1,U.S. Pat. No. 4,314,129 describes the known art as follows:

-   -   Pipe base 10 is provided with a plurality of perforations 11. A        plurality of rods 12 extend along the outside surface of the        pipe base, generally parallel to its longitudinal axis. The rods        are usually equally spaced around the outside of the pipe base.        Wire 14 is shown being wrapped around the pipe base and rods to        form a screen. The wire feeding means is not shown but is of        conventional construction usually comprising a drum from which        the wire is fed. Usually, some sort of braking arrangement is        used to hold the wire in tension to cause it to bend around the        pipe and the rods.

* * *

-   -   To wrap the wire on the pipe and rods, relative rotation between        the pipe and rods and the wire feeding means is necessary.        Usually, the wire feeding means is fixed and the pipe and rods        are rotated. At the same time the pipe and rods are moved        longitudinally at a speed which along with the speed of rotation        provides the desired spacing between the adjacent coils of wire.        Alternatively . . . the wire feeding means can be moved        longitudinally of the pipe and rods while the pipe and rods are        rotated.    -   In accordance with this invention first electrode 16 is        positioned to engage the wire as it is wrapped on the pipe and        provide a welding current that causes the wire and the rod it        engages to fuse together. The electrode is disc-shaped and rolls        along the wire. To complete the circuit, means are provided to        connect the rods to ground a short distance ahead of the wrapped        wire.    -   In the embodiment shown in FIG. 1, such means comprise second or        ground electrode 18. The ground electrode includes a plurality        of contact assemblies 20. Each assembly includes contact 22 . .        . for engaging one of the rods that extends along the surface of        the pipe base . . . . Each individual contact assembly is        attached to plate 28 . . . along a line extending radially from        the center of the pipe base. Each contact engages one of the        rods located on the outside of the pipe base.

* * *

-   -   Electrode 18 including contacts 22 should be made of a material        having good electrical conductivity, such as brass. This reduces        the tendency for any welding to occur between the contacts and        the rods. The rods are generally of steel, often stainless        steel. Housing . . . for the rod assembly as well as mounting        plate 28 should also be made of a material having good        electrical conductivity. The ground electrode assembly is        mounted on rotating head . . . for rotation with the pipe and        the rods. A commutator or the like (not shown) connects the        electrode to ground.

Embodiments of the present invention improve the known art (including,but not limited to, the processes and tools described in U.S. Pat. No.4,314,129) by providing mechanical means to: (a) adjust the contactsradially outward to overcome obstrutions protruding from the base pipe,(b) allow the welding current to have a more optimal path, and (c) otheradvantages described and/or apparent herein.

With regard to FIG. 2, a sand screen assembly 100 is shown having awire-wrap section 102 formed around a base pipe 104, wherein thewire-wrap section 102 is bounded by radially protruding obstructions 106(e.g., termination rings, load sleeves, or torque sleeves). Otherradially protruding obstructions may include nozzle rings (as for inflowcontrol or injection) or shunt tube assemblies or other externalhardware.

With respect to FIGS. 3A-3B and 4A-4B, one embodiment of the presentinvention includes an improved wire-wrapping assembly (e.g., as thatdescribed above and as shown in FIG. 1) for wrapping and welding a basepipe 104 with wire 109 across a set of axial rods 108, where the basepipe includes a radially protruding obstruction 106. The improvedwire-wrapping assembly includes a mounting ring or plate 200 for holdinga plurality of grounding electrode contacts 204. Each contact 204includes: (a) a dovetail-shaped profile 204A for mating with acorresponding groove 208 in the mounting ring 200, and (b) a contactprofile for engaging each axial rod 108. In alternative embodiments, thecontact may include the corresponding groove and the mounting ring mayinclude the dovetail-shaped profile.

In operation, to wire-wrap the base pipe 104, the contact 204 is inengagement with the axial rod 108 to provide sufficient grounding toweld the wire 109 to the axial rod 108 (as shown in FIGS. 3A and 4A). Asthe screen section is being wrapped and a protruding obstacle 106 isencountered, the contact 204 is permitted to slide in a linear directionalong the groove 108 of the mounting ring 200 radially outward to clearthe obstruction (as shown in FIGS. 3B and 4B). When coming to theobstruction, the wrapping process is stopped and the wire-wrappingassembly can be moved to a new position on the base pipe 104 even withan obstruction in place. Once clear, the contact 204 can slide radiallyinward to re-engage the rod 108.

In other embodiments, the wire-wrapping assembly may further include abiasing member (e.g., a spring) connected to each contact for biasingthe contact radially inward. The biasing member would permit the contactto slide radially outward to overcome the protruding obstruction, thenapply a sufficient force to move the contact back into engagement withthe axial rod.

In an alternative embodiment of the present invention, with respect toFIG. 5, instead of sliding engagement, the grounding electrode contacts206 are in rotating engagement with the mounting ring 200. Each contact206 includes a pin 207 for connection to the ring 200 such that thecontact is free to rotate as much as ninety (90) degrees to move thecontact completely away from the base pipe 104 and to permit clearanceof any protruding obstruction. While prior art wire-wrapping machinesincluded contacts with a very limited degree of pivot to account forminor eccentricities or ovality or other imperfections in the underlyingbase pipe, this embodiment permits a high degree of pivot in the contactas required for the wire-wrapping assembly to clear larger obstructions.

In still another embodiment of the present invention, with reference toFIG. 6, the grounding electrode contacts 204 engaging the axial rods 204connected to the base pipe 104 are located on the mounting ring 200 (orplate) as described above. The mounting ring 200 may be adapted torotate, and the rotation of this ring 200 may be synchronized with therotation of the base pipe 104. The contacts 204 engaging the axial rods108 have some degree of freedom to move radially during the wrappingprocess either to account for minor eccentricities or ovality or otherimperfections in the underlying base pipe 104 or even to movesubstantially outward to account for obstructions 106 along the basepipe 104 such as end rings (all described above). A wheel device 210 isincluded in the wire-wrapping assembly to align with the contact 204 asit moves into the spot welding position. A force F is applied againstthe contact 204 by the wheel 210 to more readily secure the contact 204against axial rod 204. This facilitates formation of a more directcurrent path than known from existing technology.

While the invention has been disclosed with respect to a limited numberof embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover such modifications and variations as fall within the truespirit and scope of the invention.

1. A method of making a sand screen on a base pipe, comprising:positioning a first plurality of rods axially along an outer surface ofthe base pipe; grounding the first plurality of rods with a plurality ofcontacts by engaging each of the first plurality of rods with acorresponding one of the plurality of contacts, wherein each of theplurality of contacts is connected to a mounting ring disposed radiallyoutward from the base pipe, wherein each contact comprises a protrusion,and each protrusion is disposed within a corresponding groove in themounting ring; wrapping a first wire around the base pipe and the firstplurality of rods; welding the first wire to the first plurality ofrods; and moving the plurality of contacts radially outward in a lineardirection by sliding the protrusion of each contact within acorresponding groove.
 2. The method of claim 1, wherein moving theplurality of contacts radially outward in a linear direction furthercomprises forming a radial gap between the plurality of contacts and anobstruction ring disposed around the base pipe.
 3. The method of claim2, further comprising moving the plurality of contacts from a firstaxial side of the obstruction ring to a second axial side of theobstruction ring.
 4. The method of claim 3, further comprising movingthe plurality of contacts radially inward in a linear direction toengage a second plurality of rods extending along the outer surface ofthe base pipe on the second axial side of the obstruction ring.
 5. Themethod of claim 4, further comprising wrapping a second wire around thebase pipe and the second plurality of rods.
 6. The method of claim 1,wherein the protrusion comprises a dovetail-shaped profile.
 7. Themethod of claim 1, wherein engaging each of the first plurality of rodswith a corresponding one of the plurality of contacts further comprisespositioning each of the first plurality of rods at least partiallywithin a slot formed in each of the corresponding contacts.
 8. Themethod of claim 1, further comprising moving the mounting ring and theplurality of contacts axially with respect to the first plurality ofrods.
 9. A method of making a sand screen on a base pipe, comprising:mounting an obstruction ring on the base pipe with the obstruction ringprotruding radially outward from the base pipe; mounting the base pipefor rotation around its longitudinal axis; positioning a first pluralityof rods along an outer surface of the base pipe on a first side of theobstruction ring portion and the second base pipe portion; rotating thebase pipe and the-rods to wrap a first wire around the first pluralityof rods with a wire wrapping assembly; moving the base pipe and the wirewrapping assembly longitudinally with respect to one another so as towrap the first wire in spaced helical coils around the first pluralityof rods; welding the first wire to the first plurality of rods as thefirst wire engages the first plurality of rods; grounding the firstplurality of rods ahead of the first wire with a plurality of contactsby engaging each of the first plurality of rods with a corresponding oneof the contacts; moving the contacts radially outward in a lineardirection after wrapping the first plurality of rods with the first wireto disengage the contacts from wounding against the first plurality ofrods to an obstruction ring clearing position where the contacts areseparated sufficiently to pass over the obstruction ring during relativelongitudinal movement between the base pipe and the wire wrappingassembly; moving the base pipe and the wire wrapping assemblylongitudinally with respect to one another after wire wrapping the firstplurality of rods so as to move the contacts over the obstruction ring;moving the contacts radially inward to engage the contacts with a secondplurality of rods positioned along the outer surface of the base pipe ona second side of the obstruction ring portion; rotating the base pipe towrap a second wire around the second plurality of rods with the wirewrapping assembly; moving the base pipe and the wire wrapping assemblylongitudinally with respect to one another so as to wrap the second wirein spaced helical coils around the second plurality of rods; and whereinan outer diameter of the obstruction ring is greater than each of anouter diameter of the wrapped first wire and the wrapped second wire onthe base pipe.
 10. The method of claim 9, wherein each contact comprisesa protrusion, and each protrusion is disposed within a correspondinggroove in a mounting ring disposed radially outward from the base pipe.11. The method of claim 10, wherein moving the contacts furthercomprises sliding the protrusion of each contact within thecorresponding groove to clear the obstruction ring.
 12. The method ofclaim 9, wherein the obstruction ring is a load sleeve.